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Michael Seeger: Genetic diversity of Clavibacter michiganensis subsp. michiganensis strains from Central Chile and their phylogenetic relationships with strains from America, Europe and Africa

  • Date: Jul 15, 2019
  • Time: 10:00 - 11:00
  • Speaker: Prof Michael Seeger from the Universidad Valparaiso, Chile
  • Here you find more information on the speaker (in Spanish): https://www.departamentoquimica.usm.cl/academicos/michael-seeger/
  • Location: MPI Plön
  • Room: Lecture hall
  • Host: Paul Rainey

Abstract:

Bacterial canker caused by Clavibacter michiganensis subsp. michiganensis (Cmm) is one of the most important bacterial diseases of tomato. In order to understand the emergence and dissemination of this pathogen in Chile, Chilean Cmm strains isolated in the period 1996-2015 from different sites in Central Chile were characterized and compared to a worldwide collection of strains. Multilocus sequence analysis and typing (MLSA-MLST) based on five housekeeping genes, and multilocus variable number of tandem repeats (VNTR) analysis (MLVA) were used. Low diversity was found using MLSA-MLST among the 25 Chilean strains, which clustered into three groups, each corresponding to a single sequence type (ST). Group I contained most strains (21/25), whereas group II contained only one strain. These two groups belonged to the same genetic lineage. Group III contained three strains. MLVA also distributed the strains into the same three groups. Group III strains shared the same ST as strains from Europe, America and Africa. Group II strains shared the same ST as strains from Brazil and Uruguay, while Group I strains shared the same ST as two strains of unknown origin. Copper and antibiotics (streptomycin, oxytetracycline and gentamicin) are commonly used in Chile to control Cmm. A search of streptomycin resistance-related genes was carried out using PCR and sequencing techniques. MIC results showed that four strains were highly sensitive to streptomycin, whereas 21 strains that belongs to Group I were resistant. The mechanism conferring high streptomycin resistance of these strains was elucidated. This study shows that Cmm strains from Central Chile tend to be clonal and have similar genetic profiles to strains from other countries. By the other hand, the continuous use of streptomycin leads to emergence of resistant Cmm strains, indicating that novel alternatives to control this plant pathogen are required.

 
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